How to wear cologne without overdoing it

If you're asking how to wear cologne without overdoing it, start with the odd part of the problem: the person least able to tell is you. After a few minutes around a smell, your nose stops reporting it. That's called olfactory fatigue, or noseblindness, and Wikipedia describes it as a normal, short-term loss of the ability to notice a smell after prolonged exposure. Sensitivity comes back once you're away from the smell for a while.

So "I can barely smell it" is a poor test. Use a fixed number of sprays instead, and adjust from what other people tell you.

How much, and where

Everything in this section is a rule of thumb, not a measured standard. Scents differ a lot in strength, so treat it as a starting point.

Start with one to three sprays total. One is plenty for a strong, concentrated fragrance. Three is the upper end for a light one.
Spray from a hand's length away. Holding the bottle about 15 cm (6 inches) from your skin spreads the mist rather than soaking one patch.
Pick spots near your body's warmth. The base of the neck, the chest under your shirt, or the inside of a wrist are common choices. Wrists are the classic spot, though some people say the scent fades faster there, so try a couple and see.
Don't rub it in. Rubbing wrists together is a habit, not a requirement. Let it dry.
Apply after you're dressed, or onto bare skin and then dress. Spraying a shirt directly can leave marks on some fabrics, so test a hidden spot first or skip it.
Do it before you head out, not in the car. The first minutes after spraying are the strongest, because the lightest notes evaporate fast. Let them settle at home.

Another rule of thumb: if someone has to be within arm's length to notice it, that's about right. If a coworker mentions it from across a table, cut back by a spray.

And don't re-spray because you've gone nose-blind. Check with a friend you trust instead.

What the label means

In everyday English, "cologne" just means a men's fragrance. Technically, eau de cologne is one specific strength. Wikipedia's perfume entry lists the usual ranges, by how much of the bottle is fragrance oil:

Label	Aromatic compounds (% of volume)
Parfum (extrait)	15 to 30%
Eau de parfum	15 to 20%
Eau de toilette	5 to 15%
Eau de cologne	2 to 3%
Eau fraîche	3% or less

These are typical ranges, and brands don't all follow them exactly. A common way to use them: a bottle that says parfum or eau de parfum is more concentrated than one that says eau de toilette, so many people use fewer sprays of it. A light eau de cologne or eau fraîche tends to fade faster, so some people use a few more.

How to pick a scent

There's no scent that works for everyone. This post doesn't cite research on which scents attract people, so treat it as personal taste. These are practical steps.

Wear a sample before buying a bottle. Many shops and online sellers offer small samples or decants. Fragrances change over time on your skin. According to Wikipedia, top notes (the first impression) evaporate quickly and base notes show up around 30 minutes after application. The scent you smell in the first minute isn't the one you'll wear all evening.
Test one at a time. Three scents in a row on one arm blur together, and your nose tires fast. Try one, then come back another day.
Wear it for a full day. Notice whether you still like it six hours in, not only at the counter.
Ask one person who'll be honest. A sibling or a close friend works. A sample of one isn't a verdict, but it can catch something unpleasant you've stopped noticing.
Match it to the season and setting. As a rule of thumb, lighter citrus and fresh scents sit better in heat, and warmer, heavier ones in cold weather. That's convention, not a law.

Plenty of people stick with one or two scents they like, and that's a simple way to start.

When to wear it and when to skip it

Cologne is optional. Clean skin and clean clothes come first, and the grooming checklist covers that order of operations. A simple skincare routine sits in the same category. Some situations call for less or none:

Small spaces. A first-date coffee table, a car, a lift, a crowded bus. Many people use one spray fewer than usual.
Gyms, workplaces, hospitals and some venues. Some ask for scent-free.
Anyone who mentions a headache or a stuffy nose. Fragrance can bother people with asthma or sensitivities. The FDA notes that for people sensitive to certain fragrances, inhaling them may cause shortness of breath. If someone near you reacts, skip it from then on.
Hot, sweaty occasions. Fragrance can't cover a missed shower. Wash first.

On a date, going lighter than you would at a club is a common default. For the rest of the outfit, see what to wear on a first date and what to wear when you go out.

If your skin reacts

Fragrance can cause allergic reactions in some people. The FDA says allergic reactions can include hives, itchy skin, a rash and flaking skin, among other symptoms. It advises consulting a healthcare professional if you suspect a reaction, and notes that sensitivity to allergens can become more severe over time. It also notes that fragrance may appear on a label only as "fragrance" or "perfume," so you can't always see what's inside.

A simple precaution is to spray a little on a small patch of skin and wait a day before wearing a new bottle properly. That's a common-sense step, not a medical test. If you get redness or itching, stop using it.

What to do next

Check what you own. Look at the label for parfum, eau de parfum, eau de toilette or eau de cologne, and set your spray count: one or two for the stronger ones, two or three for the lighter ones.
Run a one-week routine. Same number of sprays, same spots, every time. Spray the base of your neck and your chest, from about 15 cm away, after you're dressed.
Ask a friend once. "On a scale from nothing to too much, how strong is this?" Adjust by one spray either way.
Order two or three small samples if you want a new scent, and wear each on its own day.
Do a patch test on your inner forearm for a day before wearing any new fragrance out.
Go light if you're unsure on a first date, or skip it. A shower and fresh clothes come first.